Thrombectomy was initiated immediately after a drop in mean aortic pressure to less than 70 mm HG or an increase in mean pulmonary artery pressure to > 25 mm Hg were achieved. Following embolization, a 260-cm J-tipped exchange wire (Terumo, Leuven, Belgium) was advanced via the 24-French sheath into the distal right or left pulmonary artery, passing the proximal occlusion site. The thrombectomy catheter was introduced over the exchange guide wire and then advanced into a proximal occlusion site. The catheter device was gently withdrawn during aspiration. Catheter embolectomy was performed in the main pulmonary artery, right and left main and right and left lower lobe pulmonary arteries but not in upper lobe pulmonary arteries or segmental branches. Thrombectomy was discontinued as soon as the mean aortic pressure increased to > 70 mmHg or the mean pulmonary artery pressure decreased to < 25 mmHg, regardless of the angiographic result. In one animal, the right but not left embolized lung was left untreated to investigate macroscopic and microscopic changes due to embolization; the left lung was treated with the Aspirex catheter.